What is Parity: Definition and 220 Discussions

A parity bit, or check bit, is a bit added to a string of binary code. Parity bits are a simple form of error detecting code. Parity bits are generally applied to the smallest units of a communication protocol, typically 8-bit octets (bytes), although they can also be applied separately to an entire message string of bits.
The parity bit ensures that the total number of 1-bits in the string is even or odd. Accordingly, there are two variants of parity bits: even parity bit and odd parity bit. In the case of even parity, for a given set of bits, the occurrences of bits whose value is 1 are counted. If that count is odd, the parity bit value is set to 1, making the total count of occurrences of 1s in the whole set (including the parity bit) an even number. If the count of 1s in a given set of bits is already even, the parity bit's value is 0. In the case of odd parity, the coding is reversed. For a given set of bits, if the count of bits with a value of 1 is even, the parity bit value is set to 1 making the total count of 1s in the whole set (including the parity bit) an odd number. If the count of bits with a value of 1 is odd, the count is already odd so the parity bit's value is 0. Even parity is a special case of a cyclic redundancy check (CRC), where the 1-bit CRC is generated by the polynomial x+1.
If a bit is present at a point otherwise dedicated to a parity bit but is not used for parity, it may be referred to as a mark parity bit if the parity bit is always 1, or a space parity bit if the bit is always 0. In such cases where the value of the bit is constant, it may be called a stick parity bit even though its function has nothing to do with parity. The function of such bits varies with the system design, but examples of functions for such bits include timing management or identification of a packet as being of data or address significance. If its actual bit value is irrelevant to its function, the bit amounts to a don't-care term.

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  1. H

    The parity of a differential equation

    Homework Statement How do you tell whether a differenital equation has well defined parity or not? The equation I have is: x3y'' + x2y' - x(x2+1)y=0 and it asks: "Does this equation have a well-defined parity? What does this imply for the solutions of the equation?" My instinct would be...
  2. Q

    Solving seperable wavefunction in 2D infintie square well using parity operator

    Homework Statement You are given in a earlier stage of this problem that the wavefunction is separable, ie.) \Psi(x,y) = X(x)Y(y) The problem asks you to solve for the wavefunction of a particle trapped in a 2D infinite square well using Parity. ie.) solve \Psi(-x,-y) = \Psi(x,y) and...
  3. A

    Parity operator and change of variable question

    Hi, while reading the section about the parity operator from the QM book by Cohen-Tannoudji (complement F II, page 192), I found this: " Consider an arbitrary vector |\psi\rangle of \mathcal{E}_\vec{r} : |\psi\rangle = \int d^3 r \psi(\vec{r})|\vec{r} \rangle If the variable...
  4. R

    Odd parity checker using Verilog

    Homework Statement In this assignment, we will learn how to model flip-flops in the Verilog language and we will use a D flip-flop to construct a simple state machine. Our state machine will act as an “odd parity checker”, a state machine whose output is 1 when it observes an odd number of...
  5. R

    Wave function of spin 1/2 under parity

    Homework Statement How does the wave function of spin 1/2 change under parity? Homework Equations The Attempt at a Solution The behavior of the eigenfunctions of orbital angular momentum L is easily seen from their explicit form, namely spherical function Yml is multiplied by...
  6. M

    Parity of the anti neutral kaon

    Hi, very simple question: What is the parity of the anti neutral kaon?
  7. P

    Anticommutator of Parity and Boost

    Homework Statement Show that the anticommutator of parity and boost is zero. Homework Equations \{\mathcal{P},K^{i}\}=0 The Attempt at a Solution Let the anti commutator act on a state \{\mathcal{P},K^{i}\}\Psi(t,\vec{x})=\mathcal{P}K^{i}\Psi(t,\vec{x})+K^{i}\mathcal{P}\Psi(t,\vec{x})...
  8. S

    Something interesting concerning parity

    Is there a proof or way of proving that all even numbers (taking into account the definition of an even number as n=2k) end in 0,2,4,6, or 8?
  9. T

    Parity of [tex]^{9}_{5}B^{5}[/tex]

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  10. Q

    Nuclear Beta Decay (Parity, deta[L])

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  11. B

    Parity of Quarks and Electrons

    Im trying to understand parity in the Standard Model. Ive read that quarks have positive parity. However I thought that the reason electrons have negative parity is because of the a symmetry of their wave functions, and this is what defines them as fermions. Quarks are fermions as well as I...
  12. J

    Was the Original Law of Conservation of Parity Flawed?

    I had read an article about the law of conservation of parity was disproved by a columbian physicist,Chien-Shiung Wu through experimental basis. My doubt is whether there was a flaw in the original theory of the law.If yes, then where was it?
  13. S

    Anti-commutation of parity operator

    Homework Statement The parity operator is defined as P \psi (x) = \psi (-x). Show that P and p_x anti-commute, that is, \{ P,p_x \} = Pp_x + p_xP = 0 . Homework Equations P \psi (x) = \psi (-x) p_x = - i \hbar \frac{\partial}{\partial x} The Attempt at a Solution \{ P,p_x \}...
  14. N

    Stationary states for even parity potential

    Hi I know that stationary states in a system with an even potential energy function have to be either even or odd. Why does the ground state have to be even, and not odd? This is asserted in Griffiths, page 298.
  15. C

    Hawking Radiation & Parity Imbalance: Matter vs. Anti-Matter

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  16. T

    Parity of wave function corresponding to even potential

    Homework Statement Using time independent 1D Shrodinger equation, show that if V(x) is even and Psi(x) is a solution, Psi(-x) is also solution. Then, assume Psi(-x) and Psi(x) differ only by a constant, show that the constant is either +1 or -1. Homework Equations The Attempt at a...
  17. N

    Physical interpretation of Parity?

    I would like to know how can parity be physically interpreted :confused:?
  18. H

    What Does It Mean When a Particle Has a Parity of +1?

    I have a simple question about parity and semantics. (And it's coursework/textbook related, so I assume it goes here.) When someone says, "Such-and-such particle has parity of +1," does this mean that if we operate on the state representing that particle, we get back that same state times...
  19. T

    Confused about Parity Operator & Degeneracy in Quantum Mechanics

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  20. MathematicalPhysicist

    Parity and Time Reversal symmetries.

    I have a question, in Time Reversal operator, does an external magnetic field would get a minus sign, I guess that yes cause it changes direction, i.e if it's directed orthogonal to the surface then after time reversal I think it will direct anti-orthogonal to the surface, in Parity I don't...
  21. M

    Odd Parity of States: 2p m=0, 2p m=1, 26f m=0, 2s

    Homework Statement Which of the following states have odd parity? a. 2p m=0 b. 2p m=1 c. 26f m=0 d. 2s The Attempt at a Solution Knowing the wavefunctions for a,b, and d, i think that all of them have odd parity. What about the 26f m=0 state?
  22. W

    Combining Parity & CRC for Error Checking

    Hi! Recently I am studying on parity and CRC(cyclic redundancy checks) this two error checking methods. The problem is can this both methods combine to use together during transmission data? Let say I need to transfer ASCII code and I do CRC first,then before sending data I do parity on...
  23. R

    How to check if Lagrangian is parity invariant?

    The Lagrangian \mathcal L =\psi^{\dagger}\gamma^0 \gamma^\mu (1-\gamma^5)\partial_\mu \psi should violate parity, but I'm getting that it doesn't. \psi(x) changes to \gamma^0 \psi( Px) where Px=(t,-x) and x=(t,x). \gamma^j goes to - \gamma^j , while \gamma^0 stays the same...
  24. D

    Consider parity then it is no longer enough to talk about two spinors

    Ryder in chapter two of his book says that if we consider parity then it is no longer enough to talk about two spinors and so he introduces 4 spinors. Is there some postulate of Quantum physics that has to do with state trasformation under parity??
  25. H

    C and P parity of gauge bosons - what are the values?

    Can somebody explain the parities of photons, W, Z and gluons? QFT says that bosons and antibosons have the same P parity. But the P parity of the gauge bosons is rarely given. Sometimes photons are said to have negative parity, while other say this is only the case for electric dipole...
  26. N

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  27. Z

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  28. C

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  29. E

    Solving Decay & Parity Problem with J=1 & Spin 1/2 Particles

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  30. B

    Solving Parity in B.R. Martin's Nuclear and Particle Physics

    I'm reading a book: B.R. Martin's Nuclear and Particle Physics - An Introduction. In section 1.3.1 on Parity, it states the following: When dealing with p·x in the exponent, which should p and x be treated as - vectors or operators? Suppose I work it out. If exp[i(p·x-Et)] is an...
  31. C

    Shell model determining spin and parity

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  32. G

    Parity Operator: Revealing Function Parity & Its Role in Conservation

    Hi, i separated parity question from my question posted just below Parity operator reveal parity of function such that Pf = \pm f But In fact, in order to get parity of function f, we should already know parity of function In that way, Why should we know Parity operator ? we already...
  33. G

    [Q]Conserative theorem and parity

    Hi, I encountered three conserative theorem in textbook One of conserative theorem is involving my question. Liboff defined displacement operator as \hat{D}(\varsigma) = e^(\frac{i\varsigma\hat{p}_{x}}{\hbar}f(x) = f(x + \varsigma ) but is it right? If system is displaced from x...
  34. T

    Parity of permulation groups

    How do we know that half of permutations are odd and half are even? Why not 1/4, 3/4 or other proportions?
  35. G

    What is the Importance of Parity Conservation in Physics?

    Parity Conservation Means? Hello all, What is Mean By Parity Conservation?.Dont tell That When Parity Of L.H.S and R.H.S Become Equal.I want to Know the Concept Behind It.Please help Thanks
  36. E

    Spin Parity of excited 60Co

    Homework Statement I am asked to determine the most likely I\pi state for an excited 60Co nucleus (a 59Co nucleus that has just been hit by a neutron). I have determined already from the previous part of the problem that the excited state has energy of ~7 MeV compared to the ground state. Not...
  37. X

    What is the significance of parity in group theory?

    Parity vs. group theory? Parity is a special property in Quantum mechanics. I don't know whether it relates to group thery? Is it O(2), U(1), or others? Thank you!
  38. P

    How do parities add up in a two-body system in the shell model?

    I'm confused about how parities 'add up'. (I'm using the shell model of a nucleus) If you have e.g.a neutron in a d state (so l=2) and one in a p state (l=1), what is the parity of the total system? Do you have to multiply (+1*-1=-1?) or add the l values or something completely different?
  39. L

    Perturbed Ground State Wavefunction with Parity

    [SOLVED] Perturbed Ground State Wavefunction with Parity Homework Statement A particle is in a Coulomb potential H_{0}=\frac{|p|^{2}}{2m} - \frac{e^{2}}{|r|} When a perturbation V (which does not involve spin) is added, the ground state of H_{0} + V may be written |\Psi_{0}\rangle =...
  40. J

    Inertial frames and Parity symmetry

    Do you think you could give me some helpful insight to a follow up question from the discussion of defining inertial frames: I'm still having trouble figuring out a good way of incorporating parity violation into my intuition. If it wasn't for experiment showing otherwise, I probably would...
  41. Pythagorean

    How Is CP-Violation Explored in Particle Physics?

    I've gained interest in the http://lhc.web.cern.ch/lhc/" , which pertain to CP-violation. QUESTION #1 What sort of classes/branches would teach/contain 'charge conjugation' and 'parity'? QUESTION #2 the wiki article on parity states that parity is an operator- "acting on a state...
  42. T

    Why is parity maximally violated in weak interactions?

    Why do they always say parity is maximally violated in weak interaction? This is true for W boson interactions. But not for Z bosons, as the Zs couple to both left and right handed particles. And hence, is not maximally violated in the case of Z.
  43. O

    What is the physical meaning of the parity of a wavefunction?

    Can anyone help me understand what is meant by the "parity of a wavefunction"? I know in terms of even/odd parity, that: P \Psi(x,y,z) = \pm \Psi(x,y,z) ie, P = +/- 1 But I don't know what "parity of a wavefunction" physically means...
  44. H

    Cmput: 2D parity error detection scheme

    Question Details: The following blocks have been encoded using the two-dimensional parity error detection scheme. That is, the rows have been encoded using odd parity and the last row holds the parity bits of the columns which have also been encoded using odd parity. There are two possible...
  45. F

    Parity Operator, Symmetric Potential: Is V=PV?

    Let's say we have a symmetric potential, in position representation V(x)=V(-x) and let P be the parity operator. Then quite clearly PV=VP but I was told the stronger statement V=PV is not true, but I thought V=\int_{-\infty}^{\infty} V\left|x\right\rangle\left\langle x \right| dx (where I...
  46. S

    What Determines the Spin and Parity of a Nucleus with Multiple Excited Nucleons?

    I understand that the spin and parity of the nucleus is determined by looking at hte unpaired nucleon (is that the correct way of saying it?). But what if we were looking at nulceus where 2 or more nucleons were excited from the ground state?? What would the spin and parity of the nucleus be...
  47. J

    Parity of Pi0 and Its Photon Decays

    Hi, I thought pions were assigned parity of -1, but how then can the Pi0 decay into two photons with parity -1?? What am I missing? Thanks, Joe
  48. M

    Even parity => symmetric space wave function?

    If I have af wavefunction that is a product of many particle wavefunctions $\Psi = \psi_1(r_1)\psi_2(r_2) ... \psi_n(r_n)$ If I then know that the parity of $ \Psi $ is even. Can I then show that the wavefunction i symmetric under switching any two particles with each other. That is...
  49. U

    Does Parity Operator Squared Equal Identity Operator?

    just wondering... does the parity operator squared give the identity operator?
  50. I

    How can I handle stick parity in VB.NET 2005 without built-in functions?

    Hello all, Im trying to communicate with a RS232 device utilizing stick parity. This is defined as the first byte of a packet having its parity bit set to one, while all proceeding bytes have their parity bit set to 0. This was meant to be used to determine the start of a new packet...
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